Robot devices operate to automatically assemble or mate parts and tools. They are generally used in applications in which the position and orientation of all parts are carefully controlled. In applications in which misalignments do occur, it is necessary to use either active sensing devices, which can be expensive and slow, or passive accommodation devices which, although inexpensive and fast, can have limited correction range.
Remote center compliance (RCC) devices, which are passively compliant, are available for assembly, mating and insertion tasks where it is desired to quickly and easily accommodate for relatively small misalignments. Three different types of RCC devices are disclosed in U.S. Pat. Nos. 4,098,001, 4,155,169, and application Ser. No. 140,768, filed Apr. 16, 1980, now U.S. Pat. No. 4,337,579 and incorporated herein by reference. These devices have now been instrumented, U.S. patent application Ser. Nos. 76,906 now abandoned and 76,907, filed Sept. 19, 1979, now U.S. Pat. No. 4,316,329 incorporated herein by reference, so that they are able to passively adjust to assemble misaligned parts and also indicate a measure of the misalignment.
Typically, instrumented RCC (IRCC) devices are intended to measure the position and orientation of the parts very accurately over the RCC device's entire compliant range. Such measurement IRCC devices have extremely good resolution and linearity and are complex and expensive devices. In many applications accurate measurement capability is not required, and simpler devices would suffice. A number of tasks such as placing a peg in a hole and edge following, such as for routing, grinding and arc welding, do not require such accurate measurement and correction as provided by present IRCC devices.